Clipper with double-action toggle mechanism

ABSTRACT

A veneer clipper in which the movable knife is driven through a double-action toggle mechanism that is powered by a pair of reciprocable pneumatic motors. The toggle mechanism include two sets of corresponding pivoted joints, with each motor drivingly connected to a different one of such sets. One of the motors is mounted in a nontraveling position on the clipper&#39;&#39;s frame, while the other motor is mounted for travel relative to the frame, generally in the same direction as the knife.

Prentice July 17, 1973 CLIPPER WITH DOUBLE-ACTION TOGGLE MECHANISMPrimary Examiner-Andrew R. .Juhasz Assistant ExaminerJames F. Coan [76]Inventor: Thomas H. Prentice, 9015 S. W. 19th Avenue, Portland Oreg97219 Attmey-Kolisch, Hartwell & Dickinson [22] Filed: Sept. 30, 1971[2|] Appl. No.: 185,089 [57] ABSTRACT A veneer clipper in which themovable knife is driven U-S. l0, through a d uble acti0n togglemechanism that is pow- CI- cred a pair of reciprocable pneumatic motorsThe Fleld of Search toggle mechanism include two ets of corresponding74/520, 1 l0 pivoted joints, with each motor drivingly connected to adifferent one of such sets. One of the motors is References Cltedmounted in a nontraveling position on the clippers UNITED STATES PATENTSframe, while the other motor is mounted for travel rela- 2,92s,3053/1960 Heth et al. 83/630 x tive to the frame, generally in the Samedirection as the 2,691,995 1954 Carlson 83/630 x knife- FOREIGN PATENTSOR APPLICATIONS 9 Claims, 5 Drawing Figures 1,182,055 6/1959 France74/520 i /4 'III 2 II "I" I, 1] 1" t f It r 3 "It f m, L "It. 58 h, g"h,

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'l v II I 1 "HI I CLIPPER WITH DOUBLE-ACTION TOGGLE MECHANISM BACKGROUNDAND SUMMARY OF THE INVENTION This invention pertains to a clipperincluding a recriprocable knife which is driven through a double-actiontoggle mechanism. For the purpose of illustration herein, a preferredembodiment of the invention is described in conjunction with a clipperfor cutting sheets of wood veneer and the like, wherein the inventionhas been found to have particular utility.

Over the years, numerous improvements have been made in the differentkinds of equipment used in the manufacture of plywood. Many of theseimprovements have greatly increased the speed with which various ones ofthe steps leading up to the final preparation of a plywood panel can beaccomplished. However, a situation presently existing is that veneerclippers used in the preassembly cutting of veneer sheets are notcapable of keeping up with the greatly increased rate at which sheets(to be clipped) can now be supplied a clipper. In other words, the timerequired for the usual clipper to produce a cutting stroke in its knife,and to return the knife to a condition ready to undergo another cuttingstroke, is so long that sheets must be fed to a clipper at a rateconsiderably below that attainable in other machines used in plywoodmanufacturing.

A general object of the present invention, therefore, is to provide anovel clipper which practically and satisfactorily takes care of thedrawback just mentioned.

More specifically, an object of the invention is to provide such aclipper which is capable of handling present-day sheet feed ratesattainable in other machinery used in plywood manufacturing.

To attain these objects, a clipper constructed according to the presentinvention features a novel doubleaction toggle mechanism for driving amovable knife. The toggle mechanism includes two sets of correspondingpivoted toggle joints, to each of which are drivingly connected a pairof synchronously actuated pneumatic motors. The proposed togglemechanism includes a plurality of sets of toggle links, with each setincluding a central link pivotally connected adjacent its opposite endsto a pair of end links. Two of the motors mentioned act between theclippers frame and one of the sets of the toggle joints. These twomotors, are pivoted for rocking on the frame, but otherwise do nottravel relative to the frame, and are referred to herein as beingmounted in nontraveling positions on the frame. The other two motors actbetween a carrier bar (which is mounted on the central links) and theother set of toggle joints. These two motors move with the carriermember, and are referred to herein as being mounted for travel relativeto the clipper's frame.

With such mechanism, a complete cutting stroke in a knife in the clipper(which knife is carried by the toggle mechanism) is producible in a veryshort period of time in comparison with cutting stroke times attainablein presently available clippers. The use of synchronized motors, mpuntedas just generally indicated, promotes speed and reliability in theclipper.

DESCRIPTION OF THE DRAWINGS These and other objects and advantagesattained by the invention will become more fully apparent as thedescription which follows is read in conjunction with the accompanyingdrawings, wherein:

FIG. I is a fragmentary rear elevation illustrating a veneer clipperembodying the present invention;

FIG. 2 is a cross-sectional view taken generally along the line 2--2 inFIG. 1;

FIG. 3 is a simplified schematic diagram illustrating portions ofpneumatic and electrical circuits that are employed to actuate pneumaticmotors in the clipper of FIGS. 1 and 2; and

FIGS. 4 and 5 are fragmentary views, similar to the right side of FIG.1, showing various parts in the clipper in different respectivepositions which they occupy at different points in a cutting stroke.

DETAILED DESCRIPTION OF THE INVENTION Turning now to the drawings, andreferring firstto FIGS. 1 and 2, indicated generally at 10 is a woodveneer clipper embodying the present invention. The clipper includes theusual frame 12 which may be entirely conventional in construction. Frame12 herein includes an elongated overhead substantially horizontal beam14, opposite ends of which are supported on a pair of spaced apartupright leg structures 16. Extending between and suitably joined to theleg structures in the frame, at a point considerably below beam 14, isan elongated beam 18. Beam 18 is disposed with its longitudinal axissubstantially paralleling the axis of beam 14.

The generally upright rectangular space (see FIG. 1) bounded by beamsl4, l8 and leg structures 16 accom modates the passage of successivepieces of wood veneer which are to be clipped. Veneer pieces may be fedto and carried away from clipper 10 by means of conventionalpower-driven conveyor mechanisms, with such pieces travelinghorizontally through the clipper along what might be thought of as aworkpath shown generally in dash-dot lines at 20. With respect toclipper 10, veneer pieces travel in the direction of arrow 22 in FIG. 2.

Suitably mounted on top of beam 18 is a conventional clipper anvil 24.Supported directly above the anvil, through a double-action togglemechanism 26 as contemplated herein, is a conventional clipper knife, orcutting device, 28 having a cutting edge 28a. Edge 280 substantiallyparallels the top surface of the anvil. In FIGS. 1 and 2, knife 28 isshown in a fully raised position with respect to anvel 24. The distancebetween edge 28a and the top surface of the anvil under thesecircumstances is about 2 inches.

Considering the construction of toggle mechanism 26, it includes aplurality of double-action toggle assemblies 30 disposed directly aboveand distributed along knife 28. Each toggle assembly 30 comprises threelaterally spaced pairs of toggle links, including a pair of centrallinks 30a, and pairs of upper and lower links 30b, 300, respectively.The upper ends of links 30b are mounted through spaced pivot connections34 on an elongatedbar 36 which is anchored to and extends along theunderside of the central web in beam 14. The lower ends of links 30b,and the upper ends of links 30a, are mounted through spaced pivotconnections 38 on an elongated substantially horizontal bar 39. Theopposite ends of bar 39 extend longitudinally beyond the opposite endsof knife 28. The centers of links 300 are pivoted at 40 at points spacedalong an elongated member 42referred to herein as a carrier member. Thelower ends of links 30a and the upper ends of links 300 are mountedthrough spaced pivot connections 44 on an elongated substantiallyhorizontal bar 45. Bar 45 is somewhat shorter than member 42, and longerthan knife 28. The lower ends of links 30c are pivoted through spacedpivot connections 46 to the top of knife 28.

Explaining certain terminology which is used herein, links 30b, 300 arealso referred to as link portions. In addition, the parts of links 30abetween pivot connections 38, 40, and between pivot connections 40, 44,also constitute link portions. Pivot connections 38, 44 are referred toas toggle joints. Links 30a, 30b, 30c, and pivot connections 38, 44, arealso referred to herein as portions of a drive train for driving knife28.

Also included in clipper are two toggle assemblies 32. These twoassemblies are similar, and are located adjacent opposite ends of bar39. Each assembly 32 includes upper and lower laterally spaced togglelinks 32a, 32b, respectively. The upper ends of links 32a are mountedthrough pivot connections 48 on bar 36, and the lower ends of theselinks, together with the upper ends of links 32b, are mounted throughpivot connections 50 on bar 39. The lower ends of links 32b are mountedthrough pivot connections 52 on carrier member 42. Pivot connections 50are referred to herein as toggle joints.

As will be more fully explained later, with operation of the clipper,both knife 28 and carrier member 42 reciprocate vertically relative tothe frame, with knife edge 28a moving in a cutting stroke first towardand than away from anvil 24. In order to assure proper vertical movementof these two parts, two guide assemblies 54 are provided. These guideassemblies are similar in construction, each including a substantiallyvertical cylindrical bar 56 whose upper end is anchored on beam 14through a mounting 58. As can be seen clearly in FIG. 2, the guideassemblies are disposed toward the sides of blade 28 and member 42 whichface oncoming sheets of veneer. Suitably mounted on blade 28 and onmember 42 are slider blocks 60, 62, respectively, which contain verticalbores sized freely and slidably to receive bars 56. With operation ofthe clipper, and with vertical reciprocation of the knife and carriermember, blocks 60, 62 ride vertically on bars 56 to guide the movementsof the knife and carrier member.

According to the preferred embodiment of the invention as disclosedherein, two pairs of double-acting reciprocating pneumatic motors areprovided for driving knife 28 in a cutting stroke. One of these pairs ofmo tors, which might be thought of as the upper motor pair, includesmotors 64. The other pair, which might be thought of as the lower motorpair comprises motors 66. Motors 64, 66 are substantially identical inconstruction, and are conventional.

As can be seen clearly in FIG. 1, motors 64 are mounted through pivotconnections 68 on brackets 70 which are joined to the opposite ends ofbeam 14. Pivot connections 68 accommodate rocking of motors 64 in asubstantially common vertical plane- The outer ends of the rods ofmotors 64 are joined through pivot connections 72 to the opposite endsof bar 39.

Motors 66 are joined through pivot connections 76 to brackets 78 whichare anchored adjacent the opposite ends of carrier member 42. Pivotconnections 76 accommodate rocking of motors 66 in substantially thesame vertical plane mentioned above with respect to motors 64. The outerends of the rods of motors 66 are joined through pivot connections 80 tothe opposite ends of bar 45.

All of the pivot connections heretofore mentioned are disposed withtheir pivot axes substantially parallel to one another, and normal tothe plane of FIG. 1.

In FIG. 1, the right motor 64 and the left motor 66 are shown insubstantially fully contracted conditions, with the left motor 64 andthe right motor 66 shown in substantially fully extended conditions.With such the case, the links making up the various toggle assembliesare disposed at the angles shown relative to one another, and knife 28is fully raised above anvil 24. Under these circumstances it will benoted that in each toggle assembly 30, pivot connections 34, 40, 46 liealong a substantially vertical line, with pivot connection 38 located tothe right of this line in FIG. 1, and pivot connection 44 located to theleft of the line in the figure. In each toggle assembly 32, pivotconnections 48, 52 lie along a substantially vertical line, with pivotconnection 50 to the right of this line in FIG. 1.

According to the present invention, a cutting stroke in knife 28,wherein it moves downwardly toward and against, and then away from,anvil 24, results from the simultaneous coordinated operation of motors64, 66. Considering generally what takes place in such a stroke, withthe various movable parts in the clipper beginning in the positionsshown in FIG. 1, and with operation of the motors, the two motors whichare contracted extend, and the two that are extended contract. As aconsequence, toggle joints 38, 50 move toward the left in FIG. 1, andtoggle joints 44 move toward the right in the figure.

' Such movement of these joints causes downward vertical travel of bar39, member 42, bar 45 and knife 28 relative to frame 12. Morespecifically, knife 28 moves downwardly relative to bar 45, bar. 45moves downwardly relative to member 42, member 42 moves downwardlyrelative to bar 39, and bar 39 moves downwardly relative to the clipperframe. The motors rock to accommodate such vertical movement.

Midway through the stroke, the various toggle joints occupy theirover-center positions, and knife edge 281 contacts anvil 24. Motors 64,66 are then in approximately the same conditions of extension orcontraction. This situation is illustrated in FIG. 4.

With continued operation of the motors, the toggle joints pass throughtheir over-center positions, and bar 39, member 42, bar 45, and knife 28travel upwardly toward the same relative vertical positions which theyhad at the beginning of the stroke. At the conclusion of the stroke, thetwo motors which were fully extended at the beginning of the stroke arenow fully contracted, and the two that were fully contracted are nowfully extended. Knife 28 is fully raised above the anvil. This situationis shown in FIG. 5. Toggle joints 38 are now located to the left in FIG.5 of the vertical lines containing pivot connections 34, 40, 46, andtoggle joints 44 are located to the right of these lines in the figure.Toggle joints 50 are located to the left of the vertical linescontaining pivot connections 48, 52.

The clipper is now in a condition ready for another cutting stroke,wherein the reverse actions from those just described take place.

Operation of motors 64, 66, and performance of mg gle assemblies 30,thus results in a double'action drive for knife 28 which producesrelatively rapid movement of the knife in a cutting stroke. It isimportant to note in this regard that motors 66, being carried oncarrier member 42 which itself reciprocates vertically, remainthroughout in proper positions relative to bar 45 to act through thisbar upon toggle joints 44. The pivot mountings provided for the variousmotors, of course, permit suitable vertical rocking in the motors totake care of the vertical movements which occur in the movable bars andcarrier member.

Considering now the means which is provided herein for producingcoordinated simultaneous operation of the motors, such means isillustrated in FIG. 3. The specific means employed in clipper for thispurpose comprises a pneumatic system 84 which interconnects the motors,and electrical circuits for operating a valve in the pneumatic system.Included in the pneumatic system is a source 86 of air under pressure,and a main control valve 88. Valve 88 includes a valve spool which canoccupy two different positions. The valve is represented in FIG. 3 bymeans of a block diagram of its spool. More specifically, the spool isshown as a rectangular block divided into two squares, with arrowsincluded in the squares to indicate the manner in which air flow takesplace through the valve with the spool adjusted to its differentpositions. The spool in valve 88 is suitably ganged to a pair ofsolenoids 94, 96, and is shown in a condition with flow through thevalve permitted as indicated on the right side of the spool in FIG. 3.

Source 86 is connected to valve 88 through a conduit 102. An exhaustline 104 to the atmosphere is provided for the valve. Valve 88 isconnected to the rod end of the right motor 64 and to the butt end ofthe right motor 66 through conduits 108, 110. In addition, this valve isconnected through conduit 108 and conduits 112, 114 to the butt end ofthe left motor 64 and to the rod end of the left motor 66. Conduits 116,118 connect valve 88 to the butt end of the right motor 64 and to therod end of the right motor 66. Conduit 116, along with conduits 120,122, connect valve 88 to the rod end of the left motor 64 and to thebutt end of the left motor 66.

The coils in solenoids 94, 96 are connected to conventional circuitry(not shown) through which they are alternately and momentarily energizedin response to a signal indicating that a sheet of veneer is movingthrough the clipper and into a proper position to be clipped.

The spool of valve 88 is shown in a position supplying pressurized airfrom source 86 to conduit 1.08, and exhausting conduit 116 through line104. This position of the valve spool has resulted from prior momentaryenergizing of solenoid 94. Solenoids 94, 96, as shown in FIG. 3, arenonenergized.

Describing now how the means shown in FIG. 3 produces a cutting strokein knife 28, the next time that a signal (of the type generallymentioned above) occurs indicating the presence of a sheet to beclipped, it results in solenoid 96 momentarily energizing to shift thespool of valve 88 to the right in FIG. 3. On such shifting, flow takesplace as indicated at the left side of the spool in the figure. Morespecifically, pressurized air from source 86 is then supplied conduit116, and conduits 108 is exhausted. Under these circumstances, the rightmotor 64 and the left motor 66 extend, and the right motor 66 and theleft motor 64 contract-all simultaneously. The toggle joints, bars,carrier member, and knife then move in a cutting stroke as previouslydescribed in conjunction with FIGS. 4 and 5. At the conclusion of thestroke, the various movable parts occupy the positions shown in FIG. 5.

The next successive signal indicating the presence of a sheet to beclipped results in momentary energizing of solenoid 94 which returns thespool in valve 88 to the position in which it is shown in FIG. 3.Another cutting stroke then results in the knife, with the motorsreturning to the conditions illustrated in FIG. 1.

This type operation then repeats with successive sig* nals.

It will thus be appreciated that a novel drive mechanism is provided fora clipper knife, which mechanism offers a number of advantages. One ofthe more important of these advantages is that a complete cutting strokecan be produced which is considerably faster than that attainable inpresent-day clippers. More specifically, with the mechanism proposedherein, cutting strokes (full 2-inches including return) have been madewithin about 55 milliseconds-such speed permitting veneer sheet feedrates between about 800and 900 feet per minute.

This kind of fast performance is made possible by the noveldouble-action toggle assemblies, and the novel motor mountings andarrangement. It will be noted, for example, that only relatively short(distancewise) motor strokes are required to produce a relatively long(distancewise) cutting stroke.

Another advantage is that the proposed mechanism can easily beincorporated in existing clippers.

It should be understood that while a particular form of pneumatic systemis shown for operating the motors, the invention is not limited to anyspecific type of such a system.

While a preferred embodiment of the invention has been described herein,it is appreciated that variations and modifications may be made withoutdeparting from the spirit of the invention.

It is claimed and desired to secure by letters patent:

1. In a clipper for cutting sheets of veneer and like workpiecesincluding a frame and a cutting device mounted thereon for reciprocationrelative thereto,

a carrier member adjacent said cutting device mounted on said frame forreciprocation relative both to said frame and to said cutting device,

first toggle means interconnecting said frame and said carrier memberactuatable to produce reciprocation of the latter relative to theformer,

first motor means operatively interposed between said frame and saidfirst toggle means operable to actuate the latter,

second toggle means interconnecting said carrier member and said cuttingdevice actuatable to produce reciprocation of the latter relative to theformer,

second motor means operatively interposed between said carrier memberand said second toggle means operable to actuate the latter, and

means interconnecting said first and second motor means for producingsimultaneous operation thereof.

2. The clipper of claim 1, wherein said first and second toggle meanseach includes at least a pair of pivotally interconnected toggle linkportions, with one of the toggle link portions of said first togglemeans being integral with one of the toggle link portions of said secondtoggle means.

3. The clipper of claim the wherein said first motor means is drivinglyconnected to he pivot connection between the toggle link portions ofsaid first toggle means, and said second motor means is drivinglyconnected to the pivot connection between the toggle link portion ofsaid second toggle means.

4. The clipper of claim 1, wherein said first motor means is pivotallymounted on said frame, and said second motor means is pivotally mountedon said carrier member.

5. The clipper of claim 3, wherein said first motor means is pivotallymounted on said frame, and said second motor means is pivotally mountedon said carrier member.

6. In a clipper for cutting sheets of veneer and like workpiecesincluding a frame having a workpath extending therethrough and a cuttingdevice mounted on said frame for movement toward and away from saidworkpath,

a double-action toggle mechanism interconnecting said frame and saidcutting device, and actuatable to produce movement of the latter, saidtoggle mechanism including a pair of pivoted toggle joints which formpart of a drive train between the frame and cutting device, with one ofsaid joints operatively interposed between said frame and the otherjoint, and said other joint operatively interposed between said onejoint and said cutting device, and

a pair of motors for actuating said mechanism each drivingly connectedto a different one of said joints.

7. The clipper of claim 6, wherein said toggle mechanism includes acentral toggle link interposed between its said toggle joints, whichlink moves toward and away from said workpath with actuation of themechanism, and one of said motors 'is mounted for movement with saidcentral link.

8. In a clipper for cutting sheets of veneer and like workpiecesincluding a frame having a workpath extending therethrough and a cuttingdevice mounted on said frame for movement toward and away from saidworkpath,

a double-action toggle mechanism interconnecting said frame and saidcutting device, said toggle mechanism including a pair of pivoted togglejoints and being actuatable to produce movement of the cutting device,

a pair of motors for actuating said mechanism each drivingly connectedto a different one of said joints,

first mounting means mounting one of said motors in a nontravelingposition on said frame, and

second mounting means mounting the other motor for travel relative tothe frame.

9. The clipper of claim 8, wherein said first and second mounting meanseach comprises a pivot connection.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent N 3,745,868Dated July 17', 1975 I Inventor(s) Thomas H ice It is certified thaterror appears in the above-identified patent and that said LettersPatent are hereby corrected as shown below:

Claim 3 should read as shown below:

3. The clipper of claim 2, wherein said first motor means is drivinglyconnected to the pivot connection between the goggle link portions ofsaid first togglemeans, and said second motor means is drivinglyconnected to the pivot connection between the toggle link portions ofsaidsecond toggle means.

This certificate supersedes Certificate of Correction issued January 24,1974.

Signed and sealed this 24th day of September 1974.

(SEAL) Attest:

McCOY M. GIBSON JR. C. MARSHALL DANN Attesting Officer Commissioner ofPatents FORM P0405) uscoMM-oc 60376-P60 U.S. GOVERNMENT PRINTING OFFICE}I, O'SS'JQI a UNITED STATES PATENT OFFICE %CERTIFICATE OF CORRECTIONPatent No 3 ,7l S.868 Y Dated July 17, 1973 1 e f( Thomas H. Prentice Itis certified that error appears in the above-identified patent 1 andthat said Letters Patent are hereby corrected as shown below:'

Claim 3, lines 1 and 2 should read 3. The clipper of claim lQwhereinsaid first motor means is driviingly connected to the pivot connectionSigned sealed this 29th day of January 1974.

(SEAL) Attest: EDWARD M.FLETC ER,JR. RENE D. TEGTMEYER AttestingOfficgier Acting Commissioner of Patents

1. In a clipper for cutting sheets of veneer and like workpiecesincluding a frame and a cutting device mounted thereon for reciprocationrelative thereto, a carrier member adjacent said cutting device mountedon said frame for reciprocation relative both to said frame and to saidcutting device, first toggle means interconnecting said frame and saidcarrier member actuatable to produce reciprocation of the latterrelative to the former, first motor means operatively interposed betweensaid frame and said first toggle means operable to actuate the latter,second toggle means interconnecting said carrier member and said cuttingdevice actuatable to produce reciprocation of the latter relative to theformer, second motor means operatively interposed between said carriermember and said second toggle means operable to actuate the latter, andmeans interconnecting said first and second motor means for producingsimultaneous operation thereof.
 2. The clipper of claim 1, wherein saidfirst and second toggle means each includes at least a pair of pivotallyinterconnected toggle link portions, with one of the toggle linkportions of said first toggle means being integral with one of thetoggle link portions of said second toggle means.
 3. The clipper ofclaim the wherein said first motor means is drivingly connected to hepivot connection between the toggle link portions of said first togglemeans, and said second motor means is drivingly connected to the pivotconnection between the toggle link portion of said second toggle means.4. The clipper of claim 1, wherein said first motor means is pivotallymounted on said frame, and said second motor means is pivotally mountedon said carrier member.
 5. The clipper of claim 3, wherein said firstmotor means is pivotally mounted on said frame, and said second motormeans is pivotally mounted on said carrier member.
 6. In a clipper forcutting sheets of veneer and like workpieces including a frame having aworkpath extending therethrough and a cutting device mounted on saidframe for movement toward and away from said workpath, a double-actiontoggle mechanism interconnecting said frame and said cutting device, andactuatable to produce movement of the latter, said toggle mechanismincluding a pair of pivoted toggle joints which form part of a drivetrain between the frame and cutting device, with one of said jointsoperatively interposed between said frame and the other joint, and saidother joint operatively interposed between said one joint and saidcutting device, and a pair of motors for actuating said mechanism eachdrivingly connected to a different one of said joints.
 7. The clipper ofclaim 6, wherein said toggle mechanism includes a central toggle linkinterposed between its said toggle joints, which link moves toward andaway from said workpath with actuation of the mechanism, and one of saidmotors is mounted for movement with said central link.
 8. In a clipperfor cutting sheets of veneer and like workpieces including a framehaving a workpath extending therethrough and a cutting device mounted onsaid frame for movement toward and away from said workpath, adouble-action toggle mechanism interconnecting said frame and saidcutting device, said toggle mechanism including a pair of pivoted togglejoints and being actuatable to produce movement of the cutting device, apair of motors for actuating said mechanism each drivingly connected toa different one of said joints, first mounting means mounting one ofsaid motors in a nontraveling position on said frame, and secondmounting means mounting the other motor for travel relative to theframe.
 9. The clipper of claim 8, wherein said first and second mountingmeans each comprises a pivot connection.